1. Sylvia S. Mader Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor BIOLOGY 10th Edition 1 Basic Chemistry Chapter 2: pp. 20-36 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (Crystals): © Charles M. Falco/Photo Researchers, Inc.; (Salt shaker): © Erica S. Leeds + – NaCl Na Cl sodium ion (Na + ) chloride ion (Cl – ) sodium chloride (NaCl) sodium atom (Na)chlorine atom (Cl) Na + Cl – a.b.

2. 2 Outline Chemical Elements Atoms Atomic Mass and Atomic Number Periodic Table Isotopes Electrons and Energy Molecules and Compounds Chemical Bonding Ionic and Covalent Hydrogen Properties of Water Acids and Bases

3. 3 Chemical Elements Matter: Matter is defined as anything that has mass and occupies space Matter exists in three states: solid, liquid, and gas All matter (both living and non-living) is composed of 92 naturally-occurring elements 98% of body weight of organisms are primarily composed of six elements (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur—acronym CHNOPS) make up 98% of the body weight of organisms.

4. 4 Composition of Earth’s Crust versus Organisms 60 40 20 0 FeCaKSPSiAlMgNaONCH Earth’s crust organisms Element Percent by Weight Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Gunter Ziesler/Peter Arnold, Inc.

5. 5 Atomic Structure Atom is the smallest unit of an element Atoms composed of subatomic particles: Protons - positive charge; weight of approximately 1 Dalton, found in the nucleus Neutrons - no charge; weight similar to protons, found in the nucleus Electrons - negative charge; weigh 1/1836 th Dalton; found in electron shell Atoms contain specific numbers of protons, neutrons, and electrons.

6. 6 Subatomic Particles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b.a. = proton = neutron = electron Particle Atomic Mass Unit (AMU) Location Electric Charge Subatomic Particles Proton Neutron Electron +1 0 –1 1 1 0 Nucleus Electron shell c.

7. 7 Atomic Symbols Each element is represented by one or two letters to give them a unique atomic symbol H = hydrogen, Na = Sodium, C = Carbon Each atom has its own specific mass (atomic mass) Atomic mass of an atom depends on the presence of subatomic particles Atomic number = proton number; Atomic mass or mass number = protons and neutrons

8. 8 Atomic Symbol The atomic number is above the atomic symbol and the atomic mass is below the atomic symbol

9. 9 Periodic Table Elements grouped in periodic table based on characteristics Vertical columns = groups; chemically similar Horizontal rows = periods; larger and larger Atomic mass increases as you move down a group or across a period.

10. 10 Periodic Table Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Periods Groups 19 39.10 K 20 40.08 Ca 31 69.72 Ga 32 72.59 Ge 33 74.92 As 34 78.96 Se 35 79.90 Br 36 83.60 Kr 11 22.99 Na 12 24.31 Mg 13 26.98 Al 14 28.09 Si 15 30.97 P 16 32.07 S 17 35.45 Cl 18 39.95 Ar 3 6.941 Li 4 9.012 Be 5 10.81 B 6 12.01 C 7 14.01 N 8 16.00 O 9 19.00 F 10 20.18 Ne I 1 1.008 H atomic number atomic symbol 2 4.003 He VIII atomic mass IIIIIIVVVIVII

11. 11 Periodic Table Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Periods Groups 19 39.10 K 20 40.08 Ca 31 69.72 Ga 32 72.59 Ge 33 74.92 As 34 78.96 Se 35 79.90 Br 36 83.60 Kr 11 22.99 Na 12 24.31 Mg 13 26.98 Al 14 28.09 Si 15 30.97 P 16 32.07 S 17 35.45 Cl 18 39.95 Ar 3 6.941 Li 4 9.012 Be 5 10.81 B 6 12.01 C 7 14.01 N 8 16.00 O 9 19.00 F 10 20.18 Ne I 1 1.008 H atomic number atomic symbol 2 4.003 He VIII atomic mass IIIIIIVVVIVII

12. 12 Isotopes Isotopes: Atoms of the same element with a differing numbers of neutrons (and therefore have different atomic masses). e.g. see carbon below Some isotopes spontaneously decay Radioactive Give off energy in the form of rays and subatomic particles Can be used as tracers Mutagenic – Can cause cancer 12 6 Carbon 12 C 13 6 Carbon 13 C 14 6 Carbon 14 C

13. 13 Some Medical Uses for Low Level Radiation MRI, CT, Nuclear Medicine a: © Biomed Commun./Custom Medical Stock Photo; b(Right): © Hank Morgan/Rainbow; b(Left): © Mazzlota et al./Photo Researchers, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b. a. larynx thyroid gland trachea

14. 14 Some Medical Uses for High Level Radiation Radiation can kill cancer cell Radiation can preserve food longer Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: (Peaches): © Tony Freeman/PhotoEdit; b: © Geoff Tompkinson/SPL/Photo Researchers, Inc. a.b.

15. 15 Electrons and Energy Atoms normally have as many electrons as protons Opposite charges balance leaving atom neutral Electrons are attracted to the positive nucleus Revolve around nucleus in orbitals Can be pushed into higher orbitals with energy Release that energy when they fall back to lower orbital Different energy levels referred to as electron shells

16. Animation 16 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

17. 17 The Octet Rule for Distribution of Electrons Bohr models show electron shells as concentric circles around nucleus Each shell has two or more electron orbitals Innermost shell has two orbitals Others have 8 or multiples thereof The outermost electron shell determines the reactivity of the element If 3 or less – Tendency to donate electrons If 5 or more – Tendency to receive electrons

18. 18 Bohr Models of Atoms electron electron shell nucleus hydrogen 1 1 H oxygen 16 8 O carbon 12 6 C nitrogen 14 7 N sulfur S 32 16 phosphorus P 31 15 H P S C O N Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

19. 19 Compounds and Molecules Compound - when atoms of two or more different elements bond together CO 2, H 2 O, C 6 H 12 O 6, etc. Characteristics dramatically different from constituent elements Molecule and compound is used interchangeably In Biology molecule is used e.g. molecule of water (H 2 O) molecule of glucose (C 6 H 12 O 6 ) Bonds that exist between atoms in molecules contain energy

20. 20 Compounds and Molecules one molecule indicates 6 atoms of carbon indicates 6 atoms of oxygen indicates 12 atoms of hydrogen Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

21. 21 Chemical Bonding Bonds between atoms are caused by electrons in outermost shells The process of bond formation is called a reaction The intensity of simple reactions can be predicted by the periodic table If two elements are horizontally close in the table, they usually react mildly If they are horizontally far apart, they usually react vigorously

22. 22 Types of Bonds: Ionic Bonding Ionic bond - forms when electrons are transferred from one atom to another atom. Octet rule – atoms lose or gain electrons to fill their outer shells and become more stable Atoms “want” 8 electrons in outer shell If have < 4, desire to donate electrons If have > 4, desire to receive electrons Consider two elements from opposite ends of periodic table Element from right side: Has 7 electrons in outer shell “Desperately wants” one more (7+1=8) Element from left side: Has only 1 electron in outer shell “Desperately wants” to donate it (1-1=0=8)

23. 23 Types of Bonds: Ionic Bond Example Sodium (Na): Has only 1 electron in its outermost shell Chlorine (Cl): Has 7 electrons in its outermost shell In a reaction between Na and Cl Na loses an electron and becomes a positive ion (Na+) Cl gains an electron and becomes a negative ion (Cl-) Attraction of oppositely charged ions holds the two atoms together in an ionic bond

24. 24 Formation of Sodium Chloride + – NaCl Na Cl sodium ion (Na + ) chloride ion (Cl − ) sodium chloride (NaCl) sodium atom (Na)chlorine atom (Cl) Na + Cl − a.b. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (Crystals): © Charles M. Falco/Photo Researchers, Inc.; (Salt shaker): © Erica S. Leeds

25. 25 Types of Bonds: Covalent Bonds Covalent bonds result when two atoms share electrons so each atom has an octet of electrons in the outer shell (in the case of hydrogen, 2 electrons). When atoms are horizontally closer together in the periodic table The electrons are not permanently transferred from one atom to the other like in NaCl A pair of electrons from the outer shell will “time share” with one atom and then the other This also causes the atoms to remain together Known as covalent bonding Double covalent bond - when two par of electrons are shared between atoms

26. 26 Covalently Bonded Molecules The structural formula of a molecule indicates a shared pair of electrons by a line between the two atoms e.g. single covalent bond (H–H), double covalent bond (O=O), and triple covalent bond (N = N). a. Hydrogen gas b. Oxygen gas c. Methane Structural Formula Electron Model H C H HH H H OO C OO H H H H HH CH 4 O2O2 H2H2 Molecular Formula Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

27. 27 Nonpolar Covalent Bonds In nonpolar covalent bonds, sharing of electrons is equal, i.e. the electrons are not attracted to either atom to a greater degree One atom “want” (with a specific intensity) to donate electron(s) The other atom “want,” (with the same intensity) to receive electron(s) The bond electrons will spend about equal time with both atoms

28. 28 Polar Covalent Bonds With polar covalent bonds, the sharing of electrons is unequal i.e. a toms will have unequal affinity for electrons One atom “want” to donate or receive electron(s) with a specific intensity The other atom “want” to donate or receive electron(s) with a different intensity In H2O - sharing of electrons by oxygen and hydrogen is not equal; the oxygen atom with more protons attracts the electrons closer therefore assumes a partial negative charge i.e. t he atom that gets the most time with the electrons will be slightly negative

29. Animation 29 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

30. 30 Types of Bonds: Hydrogen Bonds Water (H 2 O or H–O–H) is a polar molecule Electrons spend more time with O than H’s H’s become slightly +, O slightly – When polar molecules are dissolved in water The H’s of water molecules are attracted to the negative parts of the solute molecules and form hydrogen bond This bond is a weak attractive force between the slightly positive charge of the hydrogen atom of one molecule and slightly negative charge of another atom Easily broken, but many together can be quite strong Help to maintain the proper structure and function of complex molecules such as proteins and DNA.

31. 31 Water Molecule H HH Oxygen attracts the shared electrons and is partially negative. Hydrogens are partially positive. Ball-and-stick ModelElectron ModelSpace-filling Model H hydrogen bond H H HH a. Water (H 2 O) b. Hydrogen bonding between water molecules O O O O 104.5° Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ++ –– –– ++ ++ ++

32. 32 The Chemistry of Water: Heat Capacity Water has a high heat capacity Temperature = rate of vibration of molecules Apply heat to liquid Molecules bounce faster Increases temperature But, when heat applied to water Hydrogen bonds restrain bouncing Temperature rises more slowly per unit heat Water at a given temp. has more heat than most liquids Thermal inertia – resistance to temperature change More heat required to raise water one degree than most other liquids (1 calorie per gram) Also, more heat is extracted/released when lowering water one degree than most other liquids

33. 33 Properties of Water: Heat of Vaporization High heat of vaporization To raise water from 98 to 99 ºC; ~1 calorie To raise water from 99 to 100 ºC; ~1 calorie However, large numbers of hydrogen bonds must be broken to evaporate water To raise water from 100 to 101 ºC; ~540 calories! This is why sweating (and panting) cools Evaporative cooling is best when humidity is low because evaporation occurs rapidly Evaporative cooling works poorest when humidity is high because evaporation occurs slowly

34. 34 Evaporative Cooling of Animals freezing occursevaporation occurs a. Calories lost when 1 g of liquid water freezes and calories required when 1 g of liquid water evaporates. b. Bodies of organisms cool when their heat is used to evaporate water. Gas Liquid Solid 020408060100120 600 800 80 calories Temperature (°C) Calories of Heat Energy / g 540 calories 400 200 0 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Grant Taylor/Getty Images

35. 35 Properties of Water: Heat of Fusion Heat of fusion (melting) To raise ice from -2 to -1 ºC; ~1 calorie To raise water from -1 to 0 ºC; ~1 calorie To raise water from 0 to 1 ºC; ~80 calories! This is why ice at 0 ºC keeps stuff cold MUCH longer than water at 1 ºC This is why ice is used for cooling NOT because ice is cold But because it absorbs so much heat before it will warm by one degree

36. 36 Heat Content of Water at Various Temperatures freezing occursevaporation occurs a. Calories lost when 1 g of liquid water freezes and calories required when 1 g of liquid water evaporates. Gas Liquid Solid 020408060100120 600 800 80 calories Temperature (°C) Calories of Heat Energy / g 540 calories 400 200 0 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

37. 37 Properties of Water: Water as a Solvent Solutions consist of: A solvent (the most abundant part) and A solute (less abundant part) that is dissolved in the solvent Polar compounds readily dissolve; hydrophilic Nonpolar compounds dissolve only slightly; hydrophobic Ionic compounds dissociate in water Na + Attracted to negative (O) end of H 2 O Each Na + completely surrounded by H 2 O Cl - Attracted to positive (H 2 ) end of H 2 O Each Cl - completely surrounded by H 2 O

38. 38 Properties of Water: Water as a Solvent H H HH HHH H HH H An ionic salt dissolves in water. HH Cl – Na + O O O O OO Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.        

39. 39 Properties of Water: Water as a Solvent N O O OO HH H H H A polar molecule dissolves in water. H HH HH H Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.         

40. 40 Properties of Water: Uniqueness of Ice Frozen water less dense than liquid water Otherwise, oceans and deep lakes would fill with ice from the bottom up Ice acts as an insulator on top of a frozen body of water Melting ice draws heat from the environment

41. 41 Water as a Transport Medium Water evaporates, pulling the water column from the roots to the leaves. Water molecules cling together and adhere to sides of vessels in stems. Water enters a plant at root cells. H2OH2O H2OH2O Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

42. 42 Density of Water at Various Temperatures 04100 1.0 0.9 Density (g/cm 3 ) Temperature (ºC) liquid water ice lattice Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

43. 43 A Pond in Winter Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ice layer Protists provide food for fish. River otters visit ice-covered ponds. Aquatic insects survive in air pockets. Freshwater fish take oxygen from water. Common frogs and pond turtles hibernate.

44. 44 Properties of Water: Cohesion & Adhesion Cohesive and Adhesive Cohesion – Hydrogen bonds hold water molecules tightly together i.e. allows water to flow freely without molecules separating. Adhesion – Hydrogen bonds for between water and other polar materials Allow water be drawn many meters up a tree in a tubular vessel High Surface Tension Water molecules at surface hold more tightly than below surface Amounts to an invisible “skin” on water surface Allows small nonpolar objects (like water strider) to sit on top of water

45. 45 pH of Water: Acids pH is a measure of the concentration of hydrogen ions When water ionizes or dissociates, it releases a small but equal number of hydrogen (H+) ions and hydroxide (OH-) ions Acids donate hydrogen ions Dissociate in water and release hydrogen ions (H + ) e.g. HCl → H+ + Cl Dissociation of HCl is almost total, therefore it is a strong acid Sour to taste

46. 46 pH of Water: Bases Bases remove hydrogen ions Either take up hydrogen ions (H + ) or release hydroxide ions (OH - ) Bitter to taste Sodium hydroxide is a solid with symbol NaOH In water, it dissociates into Na + and OH - Dissociation of NaOH is almost total, therefore it is a strong base

47. 47 pH Scale pH scale used to indicate acidity and alkalinity of a solution. Values range from 0-14 0 to <7 = Acidic 7 = Neutral >7 to 14 = Basic (or alkaline) Logarithmic Scale Each unit change in pH represents a change of 10X pH of 4 is 10X as acidic as pH of 5 pH of 10 is 100X more basic than pH of 8

48. 48 The pH Scale pH value 10 –1 10 –2 10 –3 10 –4 10 –5 10 –6 10 –7 10 –8 10 –9 10 –10 10 –11 10 –12 10 –13 10 –14 10 0 Examples hydrochloric acid acidic basic stomach acid, lemon juice vinegar, cola, beer tomatoes black coffee urine pure water seawater baking soda Great Salt Lake household ammonia household bleach sodium hydroxide 1 0 2 3 4 5 6 7 8 9 10 11 12 13 14 H + Ion Concentration Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

49. 49 Buffers and pH When H + is added to pure water at pH 7, pH goes down and water becomes acidic When OH - is added to pure water at pH 7, pH goes up and water becomes alkaline Buffers are solutes in water that resist change in pH When H + is added, buffer may absorb, or counter by adding OH - When OH - is added, buffer may absorb, or counter by adding H +

50. 50 Buffers in Biology Health of organisms requires maintaining pH of body fluids within narrow limits Human blood normally 7.4 (slightly alkaline) Many foods and metabolic processes add or subtract H + or OH - ions Reducing blood pH to 7.0 results in acidosis Increasing blood pH to 7.8 results in alkalosis Both life threatening situations Bicarbonate ion ( - HCO 3 ) in blood buffers pH to 7.4

51. 51 Review Chemical Elements Atoms Isotopes Molecules and Compounds Chemical Bonding Ionic and Covalent Hydrogen Properties of Water Acids and Bases

52. Sylvia S. Mader Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor BIOLOGY 10th Edition 52 Basic Chemistry Chapter 2: pp. 21-35 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (Crystals): © Charles M. Falco/Photo Researchers, Inc.; (Salt shaker): © Erica S. Leeds + – NaCl Na Cl sodium ion (Na + ) chloride ion (Cl – ) sodium chloride (NaCl) sodium atom (Na)chlorine atom (Cl) Na + Cl – a.b.